.TH deductionguidesforstd::priority_queue 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
deductionguidesforstd::priority_queue \- deductionguidesforstd::priority_queue

.SH Synopsis
   Defined in header <queue>
   template< class Comp, class Container >

   priority_queue( Comp, Container )                                  \fB(1)\fP \fI(since C++17)\fP

       -> priority_queue<typename Container::value_type, Container,
   Comp>;
   template< class InputIt,

             class Comp = std::less</*iter-value-type*/<InputIt>>,
             class Container =
   std::vector</*iter-value-type*/<InputIt> >                         \fB(2)\fP \fI(since C++17)\fP
   priority_queue( InputIt, InputIt, Comp = Comp(), Container =
   Container() )

       -> priority_queue</*iter-value-type*/<InputIt>, Container,
   Comp>;
   template< class Comp, class Container, class Alloc >

   priority_queue( Comp, Container, Alloc )                           \fB(3)\fP \fI(since C++17)\fP

       -> priority_queue<typename Container::value_type, Container,
   Comp>;
   template< class InputIt, class Alloc >

   priority_queue( InputIt, InputIt, Alloc )
       -> priority_queue</*iter-value-type*/<InputIt>,                \fB(4)\fP \fI(since C++17)\fP
                         std::vector</*iter-value-type*/<InputIt>,
   Alloc>,

                         std::less</*iter-value-type*/<InputIt>>>;
   template< class InputIt, class Comp, class Alloc >

   priority_queue( InputIt, InputIt, Comp, Alloc )
       -> priority_queue</*iter-value-type*/<InputIt>,                \fB(5)\fP \fI(since C++17)\fP

                         std::vector</*iter-value-type*/<InputIt>,
   Alloc>, Comp>;
   template< class InputIt, class Comp, class Container, class Alloc
   >

   priority_queue( InputIt, InputIt, Comp, Container, Alloc )         \fB(6)\fP \fI(since C++17)\fP

       -> priority_queue<typename Container::value_type, Container,
   Comp>;
   template< ranges::input_range R,

             class Comp = std::less<ranges::range_value_t<R>> >
   priority_queue( std::from_range_t, R&&, Comp = Comp() )            \fB(7)\fP (since C++23)
       -> priority_queue<ranges::range_value_t<R>,

                         std::vector<ranges::range_value_t<R>>,
   Comp>;
   template< ranges::input_range R, class Comp, class Alloc >

   priority_queue( std::from_range_t, R&&, Comp, Alloc )
       -> priority_queue<ranges::range_value_t<R>,                    \fB(8)\fP (since C++23)

                         std::vector<ranges::range_value_t<R>,
   Alloc>, Comp>;
   template< ranges::input_range R, class Alloc >

   priority_queue( std::from_range_t, R&&, Alloc )
       -> priority_queue<ranges::range_value_t<R>,                    \fB(9)\fP (since C++23)

                         std::vector<ranges::range_value_t<R>,
   Alloc>>;

   The following deduction guides are provided for std::priority_queue:

   1-6) Allow deduction from underlying container type and from an iterator range.
   /*iter-value-type*/<It> denotes typename std::iterator_traits<It>::value_type for
   any type It.
   7-9) Allow deduction from a std::from_range_t tag and an input_range.

   These overloads participate in overload resolution only if

     * InputIt satisfies LegacyInputIterator,
     * Comp does not satisfy Allocator,
     * Container does not satisfy Allocator,
     * for overloads (4,5),
       (since C++23) Alloc satisfies Allocator, and
     * for overloads (3,6), std::uses_allocator_v<Container, Alloc> is true.

   Note: the extent to which the library determines that a type does not satisfy
   LegacyInputIterator is unspecified, except that as a minimum integral types do not
   qualify as input iterators. Likewise, the extent to which it determines that a type
   does not satisfy Allocator is unspecified, except that as a minimum the member type
   Alloc::value_type must exist and the expression
   std::declval<Alloc&>().allocate(std::size_t{}) must be well-formed when treated as
   an unevaluated operand.

.SH Notes

       Feature-test macro       Value    Std                   Feature
   __cpp_lib_containers_ranges 202202L (C++23) Ranges-aware construction and insertion;
                                               overloads (7-9)

.SH Example


// Run this code

 #include <functional>
 #include <iostream>
 #include <queue>
 #include <vector>

 int main()
 {
     const std::vector<int> v = {1, 2, 3, 4};
     std::priority_queue pq1{std::greater<int>{}, v}; // deduces std::priority_queue<
                                                      //     int, std::vector<int>,
                                                      //     std::greater<int>>
     for (; !pq1.empty(); pq1.pop())
         std::cout << pq1.top() << ' ';
     std::cout << '\\n';

     std::priority_queue pq2{v.begin(), v.end()}; // deduces std::priority_queue<int>

     for (; !pq2.empty(); pq2.pop())
         std::cout << pq2.top() << ' ';
     std::cout << '\\n';
 }

.SH Output:

 1 2 3 4
 4 3 2 1

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

      DR    Applied to              Behavior as published              Correct behavior
   LWG 3506 C++17      deduction guides from iterator and allocator    added
                       were missing
